The Syrian town of Quseir sits just miles from the border with Lebanon and the fierce fighting there is evidence of how the war is reaching beyond Syria's borders. Lebanese militants from Hezbollah are now openly fighting alongside Syrian soldiers in Quseir. And this weekend, rockets were fired on Hezbollah areas inside Lebanon's capital Beirut. Here's NPR's Kelly McEvers.

KELLY MCEVERS, BYLINE: The latest battle for Quseir began about a week ago. That's when the Syrian army launched a ground offensive to retake Quseir from anti-government rebels. As they entered the town, the army had some help.

(SOUNDBITE OF RADIO CONVERSATION)

MCEVERS: Syrian rebels say they intercepted these radio conversations during recent battles. If that's true, the implication is clear. The men speaking on the radios are fighting with the Syrian army, but they're speaking with a Lebanese accent.

EM AHMED: (Foreign language spoken)

MCEVERS: This woman, Em Ahmed, fled Quseir for Lebanon just as the offensive started. She and her family are now living in a unfinished house.

AHMED: (Foreign language spoken)

MCEVERS: We left not because of the bombs or the air strikes or the gas attacks, she says, we left because we're afraid of Hezbollah.

For many months, the Lebanese militia, Hezbollah, was cagey about whether or not its men were fighting in Syria.

First, witnesses like Em Ahmed started coming forward, then there were the funerals. Driving down the main highway in eastern Lebanon, they're hard to miss these days. They start with cars and trucks full of young bearded guys honking horns, waving flags, firing guns.

There's guys coming out of the top of a black truck holding an AK-47. They're wearing black. They've got yellow flags coming out of the car, the Hezbollah flags.

The convoy's destination is the small town of Brital. A hearse speeds through the streets. Three enormous posters with the faces of the dead young fighters stand next to posters of Iranian ayatollahs and Hezbollah leaders.

Did these martyrs die in Quseir, we ask. A man in sunglasses carrying a walkie-talkie just smiles. The next day, Hezbollah gathers thousands of people in a nearby village to celebrate liberation day. That's the day, back in 2000, when the Israeli army ended its decades' long occupation of southern Lebanon. Hezbollah was founded in 1982 to fight the Israeli occupation.

HASSAN NASRALLAH: (Foreign language spoken)

MCEVERS: In a speech broadcast on a big screen to the crowd, Hezbollah leader Hassan Nasrallah said his organization has entered a so-called new phase and is now actively fighting inside Syria against Arabs, not Israelis. He said the rebels in Syria are not just people who want to bring down their government, but rather, an axis of players that includes the U.S., Israel and al-Qaida.

Most of the Syrian fighters, he said, are takfiris, a word he used to mean radical Sunni Muslims.

NASRALLAH: (Foreign language spoken)

MCEVERS: Nasrallah encouraged both sides of the conflict, those who support the Syrian regime and those who oppose it, to settle their differences in Syria, not in Lebanon. Then, early the next morning, two rockets were fired at a pro-Hezbollah neighborhood here in Beirut. Four people were injured. Thanassis Cambanis is a fellow at the U.S.-based Century Foundation. He wrote a book about Hezbollah. He says while the organization's admission that its fighting in Syria is new, it does not represent a cataclysmic shift for the organization.

THANASSIS CAMBANIS: We should not overstate the importance of what's happening now. I'm not saying we shouldn't be anxious that this increases the likelihood of war spreading to Lebanon. Absolutely. Hezbollah's increased involvement in Syria, Nasrallah's volatile open rhetoric is a short but significant step up an escalation ladder that makes regional war more likely and makes the Syrian conflict harder to solve. It is not a game changer.

MCEVERS: What would be a game changer is if Lebanese Sunnis decide to take on Hezbollah here at home and unleash a more regional sectarian war or if Israel decides to open up a new front with Hezbollah. Cambanis says neither player is willing to escalate to that level for now.